The Real Seawater Pre-Treatment Performance of Trimesic Acid-Based Nanofiltration Membranes Impregnated with Ethylenediamine-MWCNT

Seawater desalination is becoming vital as a means of securing a strategic and sustainable source of water around the world. Membrane-based nanofiltration (NF) is a potential choice for seawater pre-treatment in desalination plants to improve water recovery and plant reliability. The aim of this study is the synthesis of ethylenediamine-modified multiwalled carbon nanotube (EDA-MWCNT) incorporated thin film nanocomposite membranes using a molecular self-assembly approach over the ultrafiltration membrane support. The newly developed membranes were tested for their potential application in Persian Gulf seawater pretreatment using a custom-made pilot scale NF test unit. This study also includes a detailed characterization of the synthesized membranes, evaluation of their boron rejection, and antifouling characteristics. The NF corresponding to the optimal loading of EDA-MWCNT at 0.05wt% (M3) was highly negatively charged, and hydrophilic, and attained denser structures on their surface to attain the flux in the range of 12.0 to 14.0 Lm^-2h.^-1 The total dissolved solids (TDS) of the permeate declined to the lowest value of 9,635 ppm from the initial seawater TDS of 34,560 ppm. Interestingly, the rejection offered by the M3 membrane towards the monovalent ions and boron was higher than the control and other commercial NF membranes. Therefore, EDA-MWCNT as a nanofiller demonstrated its high efficiency to reduce seawater salinity to apply the membrane for water softening applications with higher efficiency than the commercial NF-90, TS-80 4040, and NF-270 membranes.